I find this game very pertinent addition to the 2600 library and it still plays very well today, especially on higher difficulty it is quite the challenge. I'd imagine a 7800 version (hint hint ?) would be stellar and quite a challenge in its own right to develop.
It seems, not unlike Planet Patrol (which after the 5th wave is truly a juggernaut...I might try save states and see if I can figure anything out), it doesn't seem to get its due respect. I know PP has some issues with ghost missiles and that certainly adds to the challenge.
Do any of you really play this title still. I'd like to get good enough at the hard setting and do a perfect run...but I'm dreaming! ??